The hitch gear according to the invention is of a type comprising a load transfer system with at least one hydraulic cylinder, called "three point", of variable length, provided between the high median point of the lift system of the tractor and a locking point connected to the implement, and at least one adjustment wheel, provided to take up a part of the load generated by the implement, said adjustment wheel being provided with a sensor for the particular load and acting on the control means for the cylinder, according to the changes in the loads supported by the adjustment wheel, for the transfer of the initial load supported by the adjustment wheel(s) to the suspension of the tractor on the side where the implement is hitched, all the while maintaining in a fairly constant manner the residual charge at the level of the adjustment wheel.
Hitch gear of this type is known, particularly from French Patent Application 2 562 752 in the name of the instant applicant, filed on Apr. 17, 1984, and published on Oct. 18, 1985. This priority document relates in particular to a hitch gear for an implement of great width comprising two adjustment wheels, one wheel provided on each side of the implement; an interface is provided between the lifting system of the tractor and the locking means of the implement, and the load transfer system can affect two hydraulic cylinders of variable length provided between the high median point of the lifting system of the tractor and a lateral locking point of the interface connected with the implement. However, it is understood that the load transfer system may comprise one single hydraulic cylinder, such as is for example the case with narrow implements like plows.
The invention relates most particularly, but not exclusively, to a hitch gear designed to be mounted in front of the tractor and to be pushed.
It is known that the transfer or transmission of the load of the implement to the tractor assures good contact with the ground, at the same time improving the traction capacity of the tractor engine. This results in an appreciable improvement of the output and a decrease in the energy expended.
However, a problem in connection with this technique has arisen. When an increase of the load is transferred to the tractor, the latter is slightly lowered because of the compression of the suspension and the wheel elements, in particular the tires. This results in a change in the working height of the implement in the vicinity of its connection to the tractor.